```html
<!DOCTYPE html>
<html lang="zh-CN">
<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>文件上传与下载技术指南</title>
    <link rel="stylesheet" href="https://cdn.staticfile.org/font-awesome/6.4.0/css/all.min.css">
    <link rel="stylesheet" href="https://cdn.staticfile.org/tailwindcss/2.2.19/tailwind.min.css">
    <link href="https://fonts.googleapis.com/css2?family=Noto+Serif+SC:wght@400;500;600;700&family=Noto+Sans+SC:wght@300;400;500;700&display=swap" rel="stylesheet">
    <script src="https://cdn.jsdelivr.net/npm/mermaid@latest/dist/mermaid.min.js"></script>
    <style>
        body {
            font-family: 'Noto Sans SC', Tahoma, Arial, Roboto, "Droid Sans", "Helvetica Neue", "Droid Sans Fallback", "Heiti SC", "Hiragino Sans GB", Simsun, sans-serif;
            color: #333;
            line-height: 1.6;
        }
        h1, h2, h3, h4 {
            font-family: 'Noto Serif SC', serif;
            font-weight: 600;
        }
        .hero {
            background: linear-gradient(135deg, #667eea 0%, #764ba2 100%);
        }
        .card {
            transition: all 0.3s ease;
            border-radius: 12px;
            overflow: hidden;
            box-shadow: 0 10px 15px -3px rgba(0, 0, 0, 0.1), 0 4px 6px -2px rgba(0, 0, 0, 0.05);
        }
        .card:hover {
            transform: translateY(-5px);
            box-shadow: 0 20px 25px -5px rgba(0, 0, 0, 0.1), 0 10px 10px -5px rgba(0, 0, 0, 0.04);
        }
        .code-block {
            background-color: #f8f9fa;
            border-left: 4px solid #667eea;
        }
        .important-note {
            border-left: 4px solid #e53e3e;
            background-color: #fff5f5;
        }
        .tip-note {
            border-left: 4px solid #38a169;
            background-color: #f0fff4;
        }
        .mermaid-container {
            background-color: white;
            padding: 20px;
            border-radius: 8px;
            box-shadow: 0 4px 6px rgba(0, 0, 0, 0.1);
        }
    </style>
</head>
<body class="bg-gray-50">
    <!-- Hero Section -->
    <section class="hero text-white py-20 px-4 md:px-0">
        <div class="container mx-auto max-w-5xl text-center">
            <h1 class="text-4xl md:text-5xl font-bold mb-6">文件上传与下载技术指南</h1>
            <p class="text-xl md:text-2xl mb-8 opacity-90">现代Web开发中的高效文件处理解决方案</p>
            <div class="flex justify-center space-x-4">
                <a href="#upload" class="px-6 py-3 bg-white text-indigo-700 font-semibold rounded-lg hover:bg-gray-100 transition duration-300">
                    <i class="fas fa-upload mr-2"></i>上传技术
                </a>
                <a href="#download" class="px-6 py-3 bg-indigo-800 text-white font-semibold rounded-lg hover:bg-indigo-900 transition duration-300">
                    <i class="fas fa-download mr-2"></i>下载技术
                </a>
            </div>
        </div>
    </section>

    <!-- Main Content -->
    <main class="container mx-auto max-w-5xl px-4 md:px-0 py-12">
        <!-- 文件上传部分 -->
        <section id="upload" class="mb-20">
            <div class="flex items-center mb-8">
                <div class="bg-indigo-100 p-3 rounded-full mr-4">
                    <i class="fas fa-upload text-indigo-600 text-xl"></i>
                </div>
                <h2 class="text-3xl font-bold text-gray-800">文件上传技术</h2>
            </div>

            <!-- 文件上传应用 -->
            <div class="card bg-white mb-8">
                <div class="p-6">
                    <h3 class="text-2xl font-semibold mb-4 text-indigo-700 flex items-center">
                        <i class="fas fa-cube mr-2"></i>文件上传的应用
                    </h3>
                    <div class="grid md:grid-cols-2 gap-6">
                        <div class="p-4 bg-blue-50 rounded-lg">
                            <h4 class="font-medium text-blue-800 mb-2 flex items-center">
                                <i class="fas fa-user-circle mr-2"></i>个人信息管理
                            </h4>
                            <p class="text-gray-700">用户头像上传、个人资料文件提交等场景，都需要通过浏览器将文件上传到服务器端存储。</p>
                        </div>
                        <div class="p-4 bg-purple-50 rounded-lg">
                            <h4 class="font-medium text-purple-800 mb-2 flex items-center">
                                <i class="fas fa-shopping-bag mr-2"></i>商品信息管理
                            </h4>
                            <p class="text-gray-700">电商平台中商品图片上传、详情页附件等都需要文件上传功能支持。</p>
                        </div>
                    </div>
                </div>
            </div>

            <!-- 文件上传原理 -->
            <div class="card bg-white mb-8">
                <div class="p-6">
                    <h3 class="text-2xl font-semibold mb-4 text-indigo-700 flex items-center">
                        <i class="fas fa-cogs mr-2"></i>文件上传原理
                    </h3>
                    <p class="mb-6 text-gray-700">文件上传本质是服务器端通过request对象获取输入流，将浏览器端上传的数据读取出来，保存到服务器端。</p>
                    
                    <div class="grid md:grid-cols-2 gap-6 mb-6">
                        <div>
                            <h4 class="font-medium text-gray-800 mb-3 flex items-center">
                                <i class="fas fa-laptop-code mr-2 text-blue-500"></i>客户端要求
                            </h4>
                            <ul class="space-y-2 text-gray-700">
                                <li class="flex items-start">
                                    <i class="fas fa-check-circle text-green-500 mt-1 mr-2"></i>
                                    <span>请求方式必须是 POST</span>
                                </li>
                                <li class="flex items-start">
                                    <i class="fas fa-check-circle text-green-500 mt-1 mr-2"></i>
                                    <span>使用 &lt;input type="file" name="file"&gt; 组件</span>
                                </li>
                                <li class="flex items-start">
                                    <i class="fas fa-check-circle text-green-500 mt-1 mr-2"></i>
                                    <span>表单必须设置 enctype="multipart/form-data"</span>
                                </li>
                            </ul>
                        </div>
                        <div>
                            <h4 class="font-medium text-gray-800 mb-3 flex items-center">
                                <i class="fas fa-server mr-2 text-purple-500"></i>服务器端处理
                            </h4>
                            <p class="text-gray-700">通过request对象获取InputStream，将浏览器提交的所有数据读取到服务器端进行处理和存储。</p>
                        </div>
                    </div>
                </div>
            </div>

            <!-- 上传开源框架 -->
            <div class="card bg-white mb-8">
                <div class="p-6">
                    <h3 class="text-2xl font-semibold mb-4 text-indigo-700 flex items-center">
                        <i class="fas fa-code-branch mr-2"></i>上传开源框架 - commons-upload
                    </h3>
                    <div class="flex flex-col md:flex-row gap-6 mb-6">
                        <div class="md:w-1/3">
                            <img src="https://cdn.nlark.com/yuque/0/2023/png/21449790/1692788747978-ff0b04e6-f087-4d01-8fc5-8b8dfac2d825.png" alt="Commons Upload 框架" class="rounded-lg shadow-md w-full">
                        </div>
                        <div class="md:w-2/3">
                            <p class="mb-4 text-gray-700">Apache 开源组织提供了一个用来处理表单文件上传的开源组件（Commons-fileupload），该组件性能优异，API使用简单，可以让开发人员轻松实现web文件上传功能。</p>
                            
                            <div class="important-note p-4 mb-4">
                                <h4 class="font-medium text-red-600 mb-2 flex items-center">
                                    <i class="fas fa-exclamation-circle mr-2"></i>依赖说明
                                </h4>
                                <p>Commons-fileupload 需要以下两个jar包支持：</p>
                                <ul class="list-disc pl-5 mt-2">
                                    <li><strong>commons-fileupload.jar</strong> - 核心上传功能</li>
                                    <li><strong>commons-io.jar</strong> - 从1.1版本开始必须的依赖</li>
                                </ul>
                            </div>
                        </div>
                    </div>
                </div>
            </div>

            <!-- 文件上传案例 -->
            <div class="card bg-white mb-8">
                <div class="p-6">
                    <h3 class="text-2xl font-semibold mb-4 text-indigo-700 flex items-center">
                        <i class="fas fa-file-upload mr-2"></i>文件上传案例
                    </h3>
                    
                    <div class="grid md:grid-cols-2 gap-6 mb-6">
                        <div>
                            <h4 class="font-medium text-gray-800 mb-3">客户端代码</h4>
                            <div class="code-block p-4 rounded-md mb-4">
                                <pre class="text-sm text-gray-800 overflow-x-auto">
&lt;form action="Upload" method="post" enctype="multipart/form-data"&gt;
    &lt;input type="file" name="photo"/&gt;
    &lt;input type="submit" value="上传"/&gt;
&lt;/form&gt;</pre>
                            </div>
                        </div>
                        <div>
                            <h4 class="font-medium text-gray-800 mb-3">服务器端关键类</h4>
                            <ul class="space-y-2 text-gray-700">
                                <li class="flex items-start">
                                    <i class="fas fa-code text-blue-500 mt-1 mr-2"></i>
                                    <span>DiskFileItemFactory - 文件项工厂</span>
                                </li>
                                <li class="flex items-start">
                                    <i class="fas fa-code text-blue-500 mt-1 mr-2"></i>
                                    <span>ServletFileUpload - 上传处理器</span>
                                </li>
                                <li class="flex items-start">
                                    <i class="fas fa-code text-blue-500 mt-1 mr-2"></i>
                                    <span>FilenameUtils - 文件名工具</span>
                                </li>
                                <li class="flex items-start">
                                    <i class="fas fa-code text-blue-500 mt-1 mr-2"></i>
                                    <span>IOUtils - IO工具类</span>
                                </li>
                            </ul>
                        </div>
                    </div>
                    
                    <div class="tip-note p-4 mb-6">
                        <h4 class="font-medium text-green-600 mb-2 flex items-center">
                            <i class="fas fa-lightbulb mr-2"></i>中文文件名处理建议
                        </h4>
                        <p>通过item.getName()获取文件名时：</p>
                        <ul class="list-disc pl-5 mt-2">
                            <li>直接改名，不使用原中文名（推荐用于图片等展示资源）</li>
                            <li>保留中文名（适用于需要下载的压缩文件等资源）</li>
                        </ul>
                    </div>
                    
                    <div class="flex justify-center">
                        <img src="https://cdn.nlark.com/yuque/0/2023/png/21449790/1692788748219-1eeff7ea-eab7-4a0c-9e83-fa8dcd329ce7.png" alt="上传流程" class="rounded-lg shadow-md max-w-full">
                    </div>
                </div>
            </div>

            <!-- 文件名重复解决方案 -->
            <div class="card bg-white mb-8">
                <div class="p-6">
                    <h3 class="text-2xl font-semibold mb-4 text-indigo-700 flex items-center">
                        <i class="fas fa-question-circle mr-2"></i>思考题：文件名重复了怎么办？
                    </h3>
                    
                    <div class="mb-6">
                        <h4 class="font-medium text-gray-800 mb-3">解决方案</h4>
                        
                        <div class="grid md:grid-cols-2 gap-6">
                            <div class="p-4 bg-indigo-50 rounded-lg">
                                <h5 class="font-medium text-indigo-800 mb-2 flex items-center">
                                    <i class="fas fa-desktop mr-2"></i>客户端参与
                                </h5>
                                <p class="text-gray-700">方案一：做文件名唯一性校验，提示用户文件名已存在（不推荐）</p>
                            </div>
                            
                            <div class="p-4 bg-purple-50 rounded-lg">
                                <h5 class="font-medium text-purple-800 mb-2 flex items-center">
                                    <i class="fas fa-server mr-2"></i>服务端解决
                                </h5>
                                <ul class="list-disc pl-5 text-gray-700">
                                    <li>方案二：重新取唯一名字（适用于图片资源）</li>
                                    <li>方案三：按日期目录存储，保留原文件名（适用于下载文件）</li>
                                </ul>
                            </div>
                        </div>
                    </div>
                    
                    <div class="mermaid-container">
                        <div class="mermaid">
                            graph TD
                                A[文件名重复问题] --> B{解决方案}
                                B --> C[客户端方案]
                                B --> D[服务端方案]
                                C --> C1[唯一性校验提示]
                                D --> D1[重命名文件]
                                D --> D2[按日期目录存储]
                        </div>
                    </div>
                </div>
            </div>

            <!-- 获取完整表单数据 -->
            <div class="card bg-white mb-8">
                <div class="p-6">
                    <h3 class="text-2xl font-semibold mb-4 text-indigo-700 flex items-center">
                        <i class="fas fa-database mr-2"></i>获取完整的表单数据
                    </h3>
                    
                    <p class="mb-6 text-gray-700">保存完整表单信息时，除了上传文件到服务器，还需要将其他表单项信息保存到对象并存储，图片信息则保存为路径。</p>
                    
                    <div class="grid md:grid-cols-2 gap-6 mb-6">
                        <div>
                            <h4 class="font-medium text-gray-800 mb-3">获取表单项数据</h4>
                            <ul class="space-y-2 text-gray-700">
                                <li class="flex items-start">
                                    <i class="fas fa-code text-blue-500 mt-1 mr-2"></i>
                                    <span>item.getFieldName() - 获取字段名</span>
                                </li>
                                <li class="flex items-start">
                                    <i class="fas fa-code text-blue-500 mt-1 mr-2"></i>
                                    <span>item.getString() - 获取字段值</span>
                                </li>
                            </ul>
                        </div>
                        <div>
                            <h4 class="font-medium text-gray-800 mb-3">BeanUtils框架</h4>
                            <p class="text-gray-700">使用BeanUtils可以更方便地将表单数据映射到JavaBean对象。</p>
                            <div class="important-note p-4 mt-3">
                                <p>需要导入：<strong>commons-beanutils.jar</strong> 和 <strong>commons-logging.jar</strong></p>
                            </div>
                        </div>
                    </div>
                    
                    <div class="flex justify-center">
                        <img src="https://cdn.nlark.com/yuque/0/2023/png/21449790/1692788748704-aa56b3a9-0e36-47ed-8e4d-d00389415176.png" alt="BeanUtils使用" class="rounded-lg shadow-md max-w-full">
                    </div>
                </div>
            </div>

            <!-- 多文件上传案例 -->
            <div class="card bg-white">
                <div class="p-6">
                    <h3 class="text-2xl font-semibold mb-4 text-indigo-700 flex items-center">
                        <i class="fas fa-files mr-2"></i>多文件上传案例
                    </h3>
                    
                    <p class="mb-6 text-gray-700">通过设置多个file输入项或允许选择多个文件，可以实现多文件的批量上传。</p>
                    
                    <div class="flex justify-center">
                        <img src="https://cdn.nlark.com/yuque/0/2023/png/21449790/1692788749153-e3374885-fca3-4b0e-ac83-47c1d811c64c.png" alt="多文件上传" class="rounded-lg shadow-md max-w-full">
                    </div>
                </div>
            </div>
        </section>

        <!-- 文件下载部分 -->
        <section id="download" class="mt-20">
            <div class="flex items-center mb-8">
                <div class="bg-green-100 p-3 rounded-full mr-4">
                    <i class="fas fa-download text-green-600 text-xl"></i>
                </div>
                <h2 class="text-3xl font-bold text-gray-800">文件下载技术</h2>
            </div>

            <div class="card bg-white">
                <div class="p-6">
                    <h3 class="text-2xl font-semibold mb-4 text-green-700 flex items-center">
                        <i class="fas fa-file-download mr-2"></i>文件下载实现方式
                    </h3>
                    
                    <div class="grid md:grid-cols-2 gap-6 mb-6">
                        <div>
                            <h4 class="font-medium text-gray-800 mb-3 flex items-center">
                                <i class="fas fa-link mr-2 text-blue-500"></i>超链接下载
                            </h4>
                            <ul class="space-y-2 text-gray-700">
                                <li class="flex items-start">
                                    <i class="fas fa-check-circle text-green-500 mt-1 mr-2"></i>
                                    <span>下载压缩文件</span>
                                </li>
                                <li class="flex items-start">
                                    <i class="fas fa-check-circle text-green-500 mt-1 mr-2"></i>
                                    <span>下载图片文件</span>
                                </li>
                                <li class="flex items-start">
                                    <i class="fas fa-check-circle text-green-500 mt-1 mr-2"></i>
                                    <span>下载中文名文件</span>
                                </li>
                            </ul>
                        </div>
                        <div>
                            <h4 class="font-medium text-gray-800 mb-3 flex items-center">
                                <i class="fas fa-code mr-2 text-purple-500"></i>Servlet下载
                            </h4>
                            <p class="text-gray-700 mb-2">当超链接无法满足需求时，可以使用Servlet实现更灵活的下载控制。</p>
                            <div class="important-note p-4">
                                <p><strong>关键点：</strong></p>
                                <ul class="list-disc pl-5 mt-2">
                                    <li>采用流的方式读写</li>
                                    <li>设置响应头部信息</li>
                                    <li>处理中文文件名问题</li>
                                </ul>
                            </div>
                        </div>
                    </div>
                    
                    <div class="code-block p-4 rounded-md mb-6">
                        <pre class="text-sm text-gray-800 overflow-x-auto">
// Servlet下载代码示例
response.setHeader("Content-disposition", "attachment;fileName="+fileName);
// 获取输入输出流进行文件传输</pre>
                    </div>
                    
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                        <img src="https://cdn.nlark.com/yuque/0/2023/png/21449790/1692788749334-c420d66d-ef43-4abf-9f9a-650656ac40eb.png" alt="下载流程" class="rounded-lg shadow-md max-w-full">
                    </div>
                </div>
            </div>
        </section>
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        <div class="container mx-auto max-w-5xl px-4 md:px-0 text-center">
            <p class="mb-2">技术小馆</p>
            <a href="http://www.yuque.com/jtostring" class="text-blue-300 hover:text-white transition duration-300">http://www.yuque.com/jtostring</a>
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```